DeCamp mine, Phelps County, Missouri, USAi

Regional Level Types
DeCamp mine	Mine
Phelps County	County
Missouri	State
USA	Country

This mine is located eight miles due south of St. James, and is connected by a spur with the Salem branch of the St. Louis and San Francisco R'y. It is situated near the crest of a ridge at an elevation of about 130 feet above the bed of Norman creek. The surrounding area is underlain by Roubidoux sandstone, which has, in this locality, a thickness of at least 150 feet.

Mining has been conducted entirely by the underground method in the progress of which three shafts and one incline have been sunk.

There are no surface indications of a sink at this place, a few boulders of brown ore having been found at the surface. The ore lies in a large circular body and has a thickness of from 2 to 18 feet. It is from 40 to 140 feet in width, and almost completely encloses a central, barren area. The longer diameter of the ore body is about 600 feet, its greatest width is 28o feet and its average thickness is about 10 feet. It lies at a depth of 80 to 95 feet below the surface and dips 5 to 10 degrees in a westerly direction. The eastern wall of the mine is not exposed but is reported to consist of a mixture of chert, sandstone, and clay, as does also the central barren area. The western wall consists of hard cherty limestone into which the ore occasionally extends a few feet before pinching out. Within the main ore body are several lenses of decomposed and hard chert. One of these was fully 100 feet long and from 2 to 3 feet thick. Filling joints and crevices in the ore, there is also considerable red clay which is very fine grained, free from grit, and shows well developed slickensides.

The overburden consists of a mixture of clay, chert, and sandstone similar to that in the east wall and in the enclosed barren area. It is usually iron stained and locally some of the decomposed cherts have been partly replaced by limonite. It has a roughly stratified structure and wherever exposed was observed to dip in the same direction as the ore.

Shaft No. 1 is 95 feet deep and is used for hoisting purposes. Shaft No. 2 was sunk as a prospect shaft to a depth of 150 feet. The first 135 feet shows residual materials, like those of the overburden. The lower 15 feet was sunk through a massive yellow to rusty brown sandstone. A 50-foot drift extending west from the bottom of the shaft encountered similar sandstone which was not ore bearing.

The ore consists largely of soft, red hematite with important quantities of hard blue specular hematite. Some soft black ore was noted at one point associated with seams of clay. It has resulted from the softening of the hard specular ore and is not hydrated. Locally, there are patches of soft yellow ocher which show direct alteration from the sulphide of iron. The hard blue ore is chiefly coarse grained and contains small cavities lined with specular hematite and crystalline quartz although some of it is exceedingly fine grained and dense, breaking with a conchoidal fracture. The coarser grained variety frequently exhibits many sulphide pseudomorphs. The ore occurring near the bottom and margins of the ore body often contains small quantities of carbonate of copper. Boulders of marcasite occur locally in the bottom of the mine. They generally have a coarse grained texture like that of the coarser grained, blue ores and contain small crystals of iron and copper sulphide lining cavities.

To January 1st, 1911, this mine has produced approximately 40,000 tons. The ore is a non-bessemer hematite which varies considerably in composition, due to rather wide fluctuations in the amount of silica and lime.